/* ---------------------------------------------------------------- */
/* (C)Copyright IBM Corp.  2007, 2008, 2019                         */
/* ---------------------------------------------------------------- */
/**
 * \file ad_gpfs_aggrs.c
 * \brief The externally used function from this file is is declared in ad_gpfs_aggrs.h
 */

/* -*- Mode: C; c-basic-offset:4 ; -*- */
/*
 *   Copyright (C) 1997-2001 University of Chicago.
 *   See COPYRIGHT notice in top-level directory.
 */


#include "adio.h"
#include "adio_cb_config_list.h"
#include "ad_gpfs.h"
#include "ad_gpfs_aggrs.h"

#ifdef AGGREGATION_PROFILE
#include "mpe.h"
#endif


#ifdef USE_DBG_LOGGING
  #define AGG_DEBUG 1
#endif

#ifndef TRACE_ERR
#  define TRACE_ERR(format...)
#endif

/* Comments copied from common:
 * This file contains four functions:
 *
 * ADIOI_Calc_aggregator()
 * ADIOI_Calc_file_domains()
 * ADIOI_Calc_my_req()
 * ADIOI_Calc_others_req()
 *
 * The last three of these were originally in ad_read_coll.c, but they are
 * also shared with ad_write_coll.c.  I felt that they were better kept with
 * the rest of the shared aggregation code.
 */

/* Discussion of values available from above:
 *
 * ADIO_Offset st_offsets[0..nprocs-1]
 * ADIO_Offset end_offsets[0..nprocs-1]
 *    These contain a list of start and end offsets for each process in
 *    the communicator.  For example, an access at loc 10, size 10 would
 *    have a start offset of 10 and end offset of 19.
 * int nprocs
 *    number of processors in the collective I/O communicator
 * ADIO_Offset min_st_offset
 * ADIO_Offset fd_start[0..nprocs_for_coll-1]
 *    starting location of "file domain"; region that a given process will
 *    perform aggregation for (i.e. actually do I/O)
 * ADIO_Offset fd_end[0..nprocs_for_coll-1]
 *    start + size - 1 roughly, but it can be less, or 0, in the case of
 *    uneven distributions
 */

/* Description from common/ad_aggregate.c.  (Does it completely apply to bg?)
 * ADIOI_Calc_aggregator()
 *
 * The intention here is to implement a function which provides basically
 * the same functionality as in Rajeev's original version of
 * ADIOI_Calc_my_req().  He used a ceiling division approach to assign the
 * file domains, and we use the same approach here when calculating the
 * location of an offset/len in a specific file domain.  Further we assume
 * this same distribution when calculating the rank_index, which is later
 *  used to map to a specific process rank in charge of the file domain.
 *
 * A better (i.e. more general) approach would be to use the list of file
 * domains only.  This would be slower in the case where the
 * original ceiling division was used, but it would allow for arbitrary
 * distributions of regions to aggregators.  We'd need to know the
 * nprocs_for_coll in that case though, which we don't have now.
 *
 * Note a significant difference between this function and Rajeev's old code:
 * this code doesn't necessarily return a rank in the range
 * 0..nprocs_for_coll; instead you get something in 0..nprocs.  This is a
 * result of the rank mapping; any set of ranks in the communicator could be
 * used now.
 *
 * Returns an integer representing a rank in the collective I/O communicator.
 *
 * The "len" parameter is also modified to indicate the amount of data
 * actually available in this file domain.
 */
/*
 * This is more general aggregator search function which does not base on the assumption
 * that each aggregator hosts the file domain with the same size
 */
int ADIOI_GPFS_Calc_aggregator(ADIO_File fd,
			      ADIO_Offset off,
			      ADIO_Offset min_off,
			      ADIO_Offset *len,
			      ADIO_Offset fd_size,
			      ADIO_Offset *fd_start,
			      ADIO_Offset *fd_end)
{
    int rank_index, rank;
    ADIO_Offset avail_bytes;
    TRACE_ERR("Entering ADIOI_GPFS_Calc_aggregator\n");

    ADIOI_Assert ( (off <= fd_end[fd->hints->cb_nodes-1] && off >= min_off && fd_start[0] >= min_off ) );

    /* binary search --> rank_index is returned */
    int ub = fd->hints->cb_nodes;
    int lb = 0;
    /* get an index into our array of aggregators */
    /* Common code for striping - bg doesn't use it but it's
       here to make diff'ing easier.
    rank_index = (int) ((off - min_off + fd_size)/ fd_size - 1);

    if (fd->hints->striping_unit > 0) {
        * wkliao: implementation for file domain alignment
           fd_start[] and fd_end[] have been aligned with file lock
	   boundaries when returned from ADIOI_Calc_file_domains() so cannot
	   just use simple arithmatic as above *
        rank_index = 0;
        while (off > fd_end[rank_index]) rank_index++;
    }
    bg does it's own striping below
    */
    rank_index = fd->hints->cb_nodes / 2;
    while ( off < fd_start[rank_index] || off > fd_end[rank_index] ) {
	if ( off > fd_end  [rank_index] ) {
	    lb = rank_index;
	    rank_index = (rank_index + ub) / 2;
	}
	else
	if ( off < fd_start[rank_index] ) {
	    ub = rank_index;
	    rank_index = (rank_index + lb) / 2;
	}
    }
    /* we index into fd_end with rank_index, and fd_end was allocated to be no
     * bigger than fd->hins->cb_nodes.   If we ever violate that, we're
     * overrunning arrays.  Obviously, we should never ever hit this abort */
    if (rank_index >= fd->hints->cb_nodes || rank_index < 0) {
        FPRINTF(stderr, "Error in ADIOI_Calc_aggregator(): rank_index(%d) >= fd->hints->cb_nodes (%d) fd_size=%lld off=%lld\n",
			rank_index,fd->hints->cb_nodes,fd_size,off);
        MPI_Abort(MPI_COMM_WORLD, 1);
    }
    /* DBG_FPRINTF ("ADIOI_GPFS_Calc_aggregator: rank_index = %d\n",
       rank_index ); */

    /*
     * remember here that even in Rajeev's original code it was the case that
     * different aggregators could end up with different amounts of data to
     * aggregate.  here we use fd_end[] to make sure that we know how much
     * data this aggregator is working with.
     *
     * the +1 is to take into account the end vs. length issue.
     */
    avail_bytes = fd_end[rank_index] + 1 - off;
    if (avail_bytes < *len && avail_bytes > 0) {
        /* this file domain only has part of the requested contig. region */

        *len = avail_bytes;
    }

    /* map our index to a rank */
    /* NOTE: FOR NOW WE DON'T HAVE A MAPPING...JUST DO 0..NPROCS_FOR_COLL */
    rank = fd->hints->ranklist[rank_index];
    TRACE_ERR("Leaving ADIOI_GPFS_Calc_aggregator\n");

    return rank;
}

/*
 * Compute a dynamic access range based file domain partition among I/O aggregators,
 * which align to the GPFS block size
 * Divide the I/O workload among "nprocs_for_coll" processes. This is
 * done by (logically) dividing the file into file domains (FDs); each
 * process may directly access only its own file domain.
 * Additional effort is to make sure that each I/O aggregator get
 * a file domain that aligns to the GPFS block size.  So, there will
 * not be any false sharing of GPFS file blocks among multiple I/O nodes.
 *
 * The common version of this now accepts a min_fd_size and striping_unit.
 * It doesn't seem necessary here (using GPFS block sizes) but keep it in mind
 * (e.g. we could pass striping unit instead of using fs_ptr->blksize).
 */
void ADIOI_GPFS_Calc_file_domains(ADIO_File fd,
	                              ADIO_Offset *st_offsets,
                                      ADIO_Offset *end_offsets,
                                      int          nprocs,
                                      int          nprocs_for_coll,
                                      ADIO_Offset *min_st_offset_ptr,
                                      ADIO_Offset **fd_start_ptr,
                                      ADIO_Offset **fd_end_ptr,
                                      ADIO_Offset *fd_size_ptr,
                                      void        *fs_ptr)
{
    ADIO_Offset min_st_offset, max_end_offset, *fd_start, *fd_end, *fd_size;
    int i, aggr;
    TRACE_ERR("Entering ADIOI_GPFS_Calc_file_domains\n");
    blksize_t blksize;

#ifdef AGGREGATION_PROFILE
    MPE_Log_event (5004, 0, NULL);
#endif

#   if AGG_DEBUG
    static char myname[] = "ADIOI_GPFS_Calc_file_domains";
    DBG_FPRINTF(stderr, "%s(%d): %d aggregator(s)\n",
	    myname,__LINE__,nprocs_for_coll);
#   endif
    if (fd->blksize <= 0)
	/* default to 1M if blksize unset */
	fd->blksize = 1048576;
    blksize = fd->blksize;

#   if AGG_DEBUG
    DBG_FPRINTF(stderr,"%s(%d): Blocksize=%ld\n",myname,__LINE__,blksize);
#   endif
/* find min of start offsets and max of end offsets of all processes */
    min_st_offset  = st_offsets [0];
    max_end_offset = end_offsets[0];
    for (i=1; i<nprocs; i++) {
        min_st_offset = ADIOI_MIN(min_st_offset, st_offsets[i]);
        max_end_offset = ADIOI_MAX(max_end_offset, end_offsets[i]);
    }

    /* DBG_FPRINTF(stderr, "_calc_file_domains, min_st_offset, max_
       = %qd, %qd\n", min_st_offset, max_end_offset );*/

    /* determine the "file domain (FD)" of each process, i.e., the portion of
       the file that will be "owned" by each process */

    ADIO_Offset gpfs_ub       = (max_end_offset +blksize-1) / blksize * blksize - 1;
    ADIO_Offset gpfs_lb       = min_st_offset / blksize * blksize;
    ADIO_Offset gpfs_ub_rdoff = (max_end_offset +blksize-1) / blksize * blksize - 1 - max_end_offset;
    ADIO_Offset gpfs_lb_rdoff = min_st_offset - min_st_offset / blksize * blksize;
    ADIO_Offset fd_gpfs_range = gpfs_ub - gpfs_lb + 1;

    int         naggs    = nprocs_for_coll;

    /* Tweak the file domains so that no fd is smaller than a threshold.  We
     * have to strike a balance between efficency and parallelism: somewhere
     * between 10k processes sending 32-byte requests and one process sending a
     * 320k request is a (system-dependent) sweet spot

    This is from the common code - the new min_fd_size parm that we didn't implement.
    (And common code uses a different declaration of fd_size so beware)

    if (fd_size < min_fd_size)
        fd_size = min_fd_size;
    */
    fd_size              = (ADIO_Offset *) ADIOI_Malloc(nprocs_for_coll * sizeof(ADIO_Offset));
    *fd_start_ptr        = (ADIO_Offset *) ADIOI_Malloc(nprocs_for_coll * sizeof(ADIO_Offset));
    *fd_end_ptr          = (ADIO_Offset *) ADIOI_Malloc(nprocs_for_coll * sizeof(ADIO_Offset));
    fd_start             = *fd_start_ptr;
    fd_end               = *fd_end_ptr;

    /* each process will have a file domain of some number of gpfs blocks, but
     * the division of blocks is not likely to be even.  Some file domains will
     * be "large" and others "small"
     *
     * Example: consider  17 blocks distributed over 3 aggregators.
     * nb_cn_small = 17/3 = 5
     * naggs_large = 17 - 3*(17/3) = 17 - 15  = 2
     * naggs_small = 3 - 2 = 1
     *
     * and you end up with file domains of {5-blocks, 6-blocks, 6-blocks}
     *
     * what about (relatively) small files?  say, a file of 1000 blocks
     * distributed over 2064 aggregators:
     * nb_cn_small = 1000/2064 = 0
     * naggs_large = 1000 - 2064*(1000/2064) = 1000
     * naggs_small = 2064 - 1000 = 1064
     * and you end up with domains of {0, 0, 0, ... 1, 1, 1 ...}
     *
     * it might be a good idea instead of having all the zeros up front, to
     * "mix" those zeros into the fd_size array.  that way, no pset/bridge-set
     * is left with zero work.  In fact, even if the small file domains aren't
     * zero, it's probably still a good idea to mix the "small" file domains
     * across the fd_size array to keep the io nodes in balance */


    ADIO_Offset n_gpfs_blk    = fd_gpfs_range / blksize;
    ADIO_Offset nb_cn_small   = n_gpfs_blk/naggs;
    ADIO_Offset naggs_large   = n_gpfs_blk - naggs * (n_gpfs_blk/naggs);
    ADIO_Offset naggs_small   = naggs - naggs_large;

#ifdef BGQPLATFORM
    if (gpfsmpio_balancecontig == 1) {
	/* File domains blocks are assigned to aggregators in a breadth-first
	 * fashion relative to the ions - additionally, file domains on the
	 * aggregators sharing the same bridgeset and ion have contiguous
	 * offsets. */

	// initialize everything to small
	for (i=0; i<naggs; i++)
	    fd_size[i] = nb_cn_small     * blksize;

	// go thru and distribute the large across the bridges

	/* bridelistoffset: agg rank list offsets using the bridgelist - each
	 * entry is created by adding up the indexes for the aggs from all
	 * previous bridges */
	int *bridgelistoffset =
	    (int *) ADIOI_Malloc(fd->hints->fs_hints.bg.numbridges*sizeof(int));
	/* tmpbridgelistnum: copy of the bridgelistnum whose entries can be
	 * decremented to keep track of bridge assignments during the actual
	 * large block assignments to the agg rank list*/
	int *tmpbridgelistnum =
	    (int *) ADIOI_Malloc(fd->hints->fs_hints.bg.numbridges*sizeof(int));

	int j;
	for (j=0;j<fd->hints->fs_hints.bg.numbridges;j++) {
	    int k, bridgerankoffset = 0;
	    for (k=0;k<j;k++) {
		bridgerankoffset += fd->hints->fs_hints.bg.bridgelistnum[k];
	    }
	    bridgelistoffset[j] = bridgerankoffset;
	}

	for (j=0;j<fd->hints->fs_hints.bg.numbridges;j++)
	    tmpbridgelistnum[j] = fd->hints->fs_hints.bg.bridgelistnum[j];
	int bridgeiter = 0;

	/* distribute the large blocks across the aggs going breadth-first
	 * across the bridgelist - this distributes the fd sizes across the
	 * ions, so later in the file domain assignment when it iterates thru
	 * the ranklist the offsets will be contiguous within the bridge and
	 * ion as well */
	for (j=0;j<naggs_large;j++) {
	    int foundbridge = 0;
	    int numbridgelistpasses = 0;
	    while (!foundbridge) {
		if (tmpbridgelistnum[bridgeiter] > 0) {
		    foundbridge = 1;
		    /*
		       printf("bridgeiter is %d tmpbridgelistnum[bridgeiter] is %d bridgelistoffset[bridgeiter] is %d\n",bridgeiter,tmpbridgelistnum[bridgeiter],bridgelistoffset[bridgeiter]);
		       printf("naggs is %d bridgeiter is %d bridgelistoffset[bridgeiter] is %d tmpbridgelistnum[bridgeiter] is %d\n",naggs, bridgeiter,bridgelistoffset[bridgeiter],tmpbridgelistnum[bridgeiter]);
		       printf("naggs is %d bridgeiter is %d setting fd_size[%d]\n",naggs, bridgeiter,bridgelistoffset[bridgeiter]+(fd->hints->bridgelistnum[bridgeiter]-tmpbridgelistnum[bridgeiter]));
		     */
		    int currentbridgelistnum =
			(fd->hints->fs_hints.bg.bridgelistnum[bridgeiter]-
			 tmpbridgelistnum[bridgeiter]);
		    int currentfdsizeindex = bridgelistoffset[bridgeiter] +
			currentbridgelistnum;
		    fd_size[currentfdsizeindex] = (nb_cn_small+1) * blksize;
		    tmpbridgelistnum[bridgeiter]--;
		}
		if (bridgeiter == (fd->hints->fs_hints.bg.numbridges-1)) {
		    /* guard against infinite loop - should only ever make 1 pass
		     * thru bridgelist */
		    ADIOI_Assert(numbridgelistpasses == 0);
		    numbridgelistpasses++;
		    bridgeiter = 0;
		}
		else
		    bridgeiter++;
	    }
	}
	ADIOI_Free(tmpbridgelistnum);
	ADIOI_Free(bridgelistoffset);

    } else {
	/* BG/L- and BG/P-style distribution of file domains: simple allocation of
	 * file domins to each aggregator */
	for (i=0; i<naggs; i++) {
	    if (i < naggs_large) {
		fd_size[i] = (nb_cn_small+1) * blksize;
	    } else {
		fd_size[i] = nb_cn_small     * blksize;
	    }
	}
    }
#ifdef balancecontigtrace
    int myrank;
    MPI_Comm_rank(fd->comm,&myrank);
    if (myrank == 0) {
      fprintf(stderr,"naggs_small is %d nb_cn_small is %d\n",naggs_small,nb_cn_small);
	for (i=0; i<naggs; i++) {
	    fprintf(stderr,"fd_size[%d] set to %d agg rank is %d\n",i,fd_size[i],fd->hints->ranklist[i]);
	}
    }
#endif

#else // not BGQ platform
	for (i=0; i<naggs; i++) {
	    if (i < naggs_large) {
		fd_size[i] = (nb_cn_small+1) * blksize;
	    } else {
		fd_size[i] = nb_cn_small     * blksize;
	    }
    }

#endif


#   if AGG_DEBUG
     DBG_FPRINTF(stderr,"%s(%d): "
                   "gpfs_ub       %llu, "
                   "gpfs_lb       %llu, "
                   "gpfs_ub_rdoff %llu, "
                   "gpfs_lb_rdoff %llu, "
                   "fd_gpfs_range %llu, "
                   "n_gpfs_blk    %llu, "
                   "nb_cn_small   %llu, "
                   "naggs_large   %llu, "
                   "naggs_small   %llu, "
                   "\n",
                   myname,__LINE__,
                   gpfs_ub      ,
                   gpfs_lb      ,
                   gpfs_ub_rdoff,
                   gpfs_lb_rdoff,
                   fd_gpfs_range,
                   n_gpfs_blk   ,
                   nb_cn_small  ,
                   naggs_large  ,
                   naggs_small
                   );
#   endif

    fd_size[0]       -= gpfs_lb_rdoff;
    fd_size[naggs-1] -= gpfs_ub_rdoff;

    /* compute the file domain for each aggr */
    ADIO_Offset offset = min_st_offset;
    for (aggr=0; aggr<naggs; aggr++) {
        fd_start[aggr] = offset;
        fd_end  [aggr] = offset + fd_size[aggr] - 1;
        offset += fd_size[aggr];
    }

    *fd_size_ptr = fd_size[0];
    *min_st_offset_ptr = min_st_offset;

#ifdef AGGREGATION_PROFILE
    MPE_Log_event (5005, 0, NULL);
#endif
    ADIOI_Free (fd_size);
    TRACE_ERR("Leaving ADIOI_GPFS_Calc_file_domains\n");
}

/*
 * ADIOI_GPFS_Calc_my_req() overrides ADIOI_Calc_my_req for the default implementation
 * is specific for static file domain partitioning.
 *
 * ADIOI_Calc_my_req() - calculate what portions of the access requests
 * of this process are located in the file domains of various processes
 * (including this one)
 */
void ADIOI_GPFS_Calc_my_req(ADIO_File fd, ADIO_Offset *offset_list, ADIO_Offset *len_list,
			   int contig_access_count, ADIO_Offset
			   min_st_offset, ADIO_Offset *fd_start,
			   ADIO_Offset *fd_end, ADIO_Offset fd_size,
			   int nprocs,
			   int *count_my_req_procs_ptr,
			   int **count_my_req_per_proc_ptr,
			   ADIOI_Access **my_req_ptr,
			   int **buf_idx_ptr)
/* Possibly reconsider if buf_idx's are ok as int's, or should they be aints/offsets?
   They are used as memory buffer indices so it seems like the 2G limit is in effect */
{
    int *count_my_req_per_proc, count_my_req_procs, *buf_idx;
    int i, l, proc;
    ADIO_Offset fd_len, rem_len, curr_idx, off;
    ADIOI_Access *my_req;
    TRACE_ERR("Entering ADIOI_GPFS_Calc_my_req\n");

#ifdef AGGREGATION_PROFILE
    MPE_Log_event (5024, 0, NULL);
#endif
    *count_my_req_per_proc_ptr = (int *) ADIOI_Calloc(nprocs,sizeof(int));
    count_my_req_per_proc = *count_my_req_per_proc_ptr;
/* count_my_req_per_proc[i] gives the no. of contig. requests of this
   process in process i's file domain. calloc initializes to zero.
   I'm allocating memory of size nprocs, so that I can do an
   MPI_Alltoall later on.*/

    buf_idx = (int *) ADIOI_Malloc(nprocs*sizeof(int));
/* buf_idx is relevant only if buftype_is_contig.
   buf_idx[i] gives the index into user_buf where data received
   from proc. i should be placed. This allows receives to be done
   without extra buffer. This can't be done if buftype is not contig. */

    /* initialize buf_idx to -1 */
    for (i=0; i < nprocs; i++) buf_idx[i] = -1;

    /* one pass just to calculate how much space to allocate for my_req;
     * contig_access_count was calculated way back in ADIOI_Calc_my_off_len()
     */
    for (i=0; i < contig_access_count; i++) {
	/* short circuit offset/len processing if len == 0
	 * 	(zero-byte  read/write */
	if (len_list[i] == 0)
		continue;
	off = offset_list[i];
	fd_len = len_list[i];
	/* note: we set fd_len to be the total size of the access.  then
	 * ADIOI_Calc_aggregator() will modify the value to return the
	 * amount that was available from the file domain that holds the
	 * first part of the access.
	 */
  /* BES */
	proc = ADIOI_GPFS_Calc_aggregator(fd, off, min_st_offset, &fd_len, fd_size,
				     fd_start, fd_end);
	count_my_req_per_proc[proc]++;

	/* figure out how much data is remaining in the access (i.e. wasn't
	 * part of the file domain that had the starting byte); we'll take
	 * care of this data (if there is any) in the while loop below.
	 */
	rem_len = len_list[i] - fd_len;

	while (rem_len > 0) {
	    off += fd_len; /* point to first remaining byte */
	    fd_len = rem_len; /* save remaining size, pass to calc */
	    proc = ADIOI_GPFS_Calc_aggregator(fd, off, min_st_offset, &fd_len,
					 fd_size, fd_start, fd_end);

	    count_my_req_per_proc[proc]++;
	    rem_len -= fd_len; /* reduce remaining length by amount from fd */
	}
    }

/* now allocate space for my_req, offset, and len */

    *my_req_ptr = (ADIOI_Access *)
	ADIOI_Malloc(nprocs*sizeof(ADIOI_Access));
    my_req = *my_req_ptr;

    count_my_req_procs = 0;
    for (i=0; i < nprocs; i++) {
	if (count_my_req_per_proc[i]) {
	    my_req[i].offsets = (ADIO_Offset *)
		ADIOI_Malloc(count_my_req_per_proc[i] * sizeof(ADIO_Offset));
	    my_req[i].lens =
		ADIOI_Malloc(count_my_req_per_proc[i] * sizeof(ADIO_Offset));
	    count_my_req_procs++;
	}
	my_req[i].count = 0;  /* will be incremented where needed
				      later */
    }

/* now fill in my_req */
    curr_idx = 0;
    for (i=0; i<contig_access_count; i++) {
	/* short circuit offset/len processing if len == 0
	 * 	(zero-byte  read/write */
	if (len_list[i] == 0)
		continue;
	off = offset_list[i];
	fd_len = len_list[i];
	proc = ADIOI_GPFS_Calc_aggregator(fd, off, min_st_offset, &fd_len, fd_size,
				     fd_start, fd_end);

	/* for each separate contiguous access from this process */
	if (buf_idx[proc] == -1)
  {
    ADIOI_Assert(curr_idx == (int) curr_idx);
    buf_idx[proc] = (int) curr_idx;
  }

	l = my_req[proc].count;
	curr_idx += fd_len;

	rem_len = len_list[i] - fd_len;

	/* store the proc, offset, and len information in an array
         * of structures, my_req. Each structure contains the
         * offsets and lengths located in that process's FD,
	 * and the associated count.
	 */
	my_req[proc].offsets[l] = off;
	my_req[proc].lens[l] = fd_len;
	my_req[proc].count++;

	while (rem_len > 0) {
	    off += fd_len;
	    fd_len = rem_len;
	    proc = ADIOI_GPFS_Calc_aggregator(fd, off, min_st_offset, &fd_len,
					 fd_size, fd_start, fd_end);

	    if (buf_idx[proc] == -1)
      {
        ADIOI_Assert(curr_idx == (int) curr_idx);
        buf_idx[proc] = (int) curr_idx;
      }

	    l = my_req[proc].count;
	    curr_idx += fd_len;
	    rem_len -= fd_len;

	    my_req[proc].offsets[l] = off;
	    my_req[proc].lens[l] = fd_len;
	    my_req[proc].count++;
	}
    }



#ifdef AGG_DEBUG
    for (i=0; i<nprocs; i++) {
	if (count_my_req_per_proc[i] > 0) {
	    DBG_FPRINTF(stderr, "data needed from %d (count = %d):\n", i,
		    my_req[i].count);
	    for (l=0; l < my_req[i].count; l++) {
		DBG_FPRINTF(stderr, "   off[%d] = %lld, len[%d] = %lld\n", l,
			my_req[i].offsets[l], l, my_req[i].lens[l]);
	    }
	}
	DBG_FPRINTF(stderr, "buf_idx[%d] = 0x%x\n", i, buf_idx[i]);
    }
#endif

    *count_my_req_procs_ptr = count_my_req_procs;
    *buf_idx_ptr = buf_idx;
#ifdef AGGREGATION_PROFILE
    MPE_Log_event (5025, 0, NULL);
#endif
    TRACE_ERR("Leaving ADIOI_GPFS_Calc_my_req\n");
}

/*
 * ADIOI_Calc_others_req (copied to bg and switched to all to all for performance)
 *
 * param[in]  count_my_req_procs        Number of processes whose file domain my
 *                                        request touches.
 * param[in]  count_my_req_per_proc     count_my_req_per_proc[i] gives the no. of
 *                                        contig. requests of this process in
 *                                        process i's file domain.
 * param[in]  my_req                    A structure defining my request
 * param[in]  nprocs                    Number of nodes in the block
 * param[in]  myrank                    Rank of this node
 * param[out] count_others_req_proc_ptr Number of processes whose requests lie in
 *                                        my process's file domain (including my
 *                                        process itself)
 * param[out] others_req_ptr            Array of other process' requests that lie
 *                                        in my process's file domain
 */
void ADIOI_GPFS_Calc_others_req(ADIO_File fd, int count_my_req_procs,
				int *count_my_req_per_proc,
				ADIOI_Access *my_req,
				int nprocs, int myrank,
				int *count_others_req_procs_ptr,
				ADIOI_Access **others_req_ptr)
{
    TRACE_ERR("Entering ADIOI_GPFS_Calc_others_req\n");
/* determine what requests of other processes lie in this process's
   file domain */

/* count_others_req_procs = number of processes whose requests lie in
   this process's file domain (including this process itself)
   count_others_req_per_proc[i] indicates how many separate contiguous
   requests of proc. i lie in this process's file domain. */

    int *count_others_req_per_proc, count_others_req_procs;
    int i;
    ADIOI_Access *others_req;

    /* Parameters for MPI_Alltoallv */
    int *scounts, *sdispls, *rcounts, *rdispls;

/* first find out how much to send/recv and from/to whom */
#ifdef AGGREGATION_PROFILE
    MPE_Log_event (5026, 0, NULL);
#endif
    /* Send 1 int to each process.  count_my_req_per_proc[i] is the number of
     * requests that my process will do to the file domain owned by process[i].
     * Receive 1 int from each process.  count_others_req_per_proc[i] is the number of
     * requests that process[i] will do to the file domain owned by my process.
     */
    count_others_req_per_proc = (int *) ADIOI_Malloc(nprocs*sizeof(int));
/*     cora2a1=timebase(); */
/*for(i=0;i<nprocs;i++) ?*/
    MPI_Alltoall(count_my_req_per_proc, 1, MPI_INT,
		 count_others_req_per_proc, 1, MPI_INT, fd->comm);

/*     total_cora2a+=timebase()-cora2a1; */

    /* Allocate storage for an array of other nodes' accesses of our
     * node's file domain.  Also allocate storage for the alltoallv
     * parameters.
     */
    *others_req_ptr = (ADIOI_Access *)
	ADIOI_Malloc(nprocs*sizeof(ADIOI_Access));
    others_req = *others_req_ptr;

    scounts = ADIOI_Malloc(nprocs*sizeof(int));
    sdispls = ADIOI_Malloc(nprocs*sizeof(int));
    rcounts = ADIOI_Malloc(nprocs*sizeof(int));
    rdispls = ADIOI_Malloc(nprocs*sizeof(int));

    /* If process[i] has any requests in my file domain,
     *   initialize an ADIOI_Access structure that will describe each request
     *   from process[i].  The offsets, lengths, and buffer pointers still need
     *   to be obtained to complete the setting of this structure.
     */
    count_others_req_procs = 0;
    for (i=0; i<nprocs; i++) {
	if (count_others_req_per_proc[i])
  {
	    others_req[i].count = count_others_req_per_proc[i];

	    others_req[i].offsets = (ADIO_Offset *)
		ADIOI_Malloc(count_others_req_per_proc[i]*sizeof(ADIO_Offset));
	    others_req[i].lens =
		ADIOI_Malloc(count_others_req_per_proc[i]*sizeof(ADIO_Offset));

	    others_req[i].mem_ptrs = (MPI_Aint *)
		ADIOI_Malloc(count_others_req_per_proc[i]*sizeof(MPI_Aint));

	    count_others_req_procs++;
	}
	else
	{
	    others_req[i].count = 0;
	    others_req[i].offsets = NULL;
	    others_req[i].lens    = NULL;
	}
    }

    /* Now send the calculated offsets and lengths to respective processes */

    /************************/
    /* Exchange the offsets */
    /************************/

    // Figure out the layout for the sendbuf and recvbuf.
    // scounts[] and sdisps[]  /  rcounts[] and rdisps[] define the layout,
    // and the data for each section will come from from my_req[i].offsets
    // or others_req[i].offsets.

    int scount_total = 0;
    int rcount_total = 0;
    for (i=0; i<nprocs; i++)
    {
	/* Send these offsets to process i.*/
	scounts[i] = count_my_req_per_proc[i];
	sdispls[i] = scount_total;
        scount_total += scounts[i];

	/* Receive these offsets from process i.*/
	rcounts[i] = count_others_req_per_proc[i];
	rdispls[i] = rcount_total;
        rcount_total += rcounts[i];
    }

    void *sbuf_copy_of_req_info;
    void *rbuf_copy_of_req_info;

    sbuf_copy_of_req_info = (ADIO_Offset *) ADIOI_Malloc(scount_total * sizeof(ADIO_Offset));
    rbuf_copy_of_req_info = (ADIO_Offset *) ADIOI_Malloc(rcount_total * sizeof(ADIO_Offset));
    for (i=0; i<nprocs; i++)
    {
        // I haven't timed it, I'm just assuming a memcpy(,,0) is fast for
        // the entries that don't have data to contribute so I didn't bother
        // with an 'if' statement
        memcpy(sbuf_copy_of_req_info + sdispls[i] * sizeof(ADIO_Offset),
            my_req[i].offsets,
            scounts[i] * sizeof(ADIO_Offset));
    }

    /* Exchange the offsets */
    MPI_Alltoallv(sbuf_copy_of_req_info,
		  scounts, sdispls, ADIO_OFFSET,
		  rbuf_copy_of_req_info,
		  rcounts, rdispls, ADIO_OFFSET,
		  fd->comm);
    for (i=0; i<nprocs; i++)
    {
        memcpy(others_req[i].offsets,
            rbuf_copy_of_req_info + rdispls[i] * sizeof(ADIO_Offset),
            rcounts[i] * sizeof(ADIO_Offset));
    }

    /************************/
    /* Exchange the lengths */
    /************************/

    for (i=0; i<nprocs; i++)
    {
        memcpy(sbuf_copy_of_req_info + sdispls[i] * sizeof(ADIO_Offset),
            my_req[i].lens,
            scounts[i] * sizeof(ADIO_Offset));
    }

    /* Exchange the lengths */
    MPI_Alltoallv(sbuf_copy_of_req_info,
		  scounts, sdispls, ADIO_OFFSET,
		  rbuf_copy_of_req_info,
		  rcounts, rdispls, ADIO_OFFSET,
		  fd->comm);
    for (i=0; i<nprocs; i++)
    {
        memcpy(others_req[i].lens,
            rbuf_copy_of_req_info + rdispls[i] * sizeof(ADIO_Offset),
            rcounts[i] * sizeof(ADIO_Offset));
    }

    /* Clean up */
    ADIOI_Free(sbuf_copy_of_req_info);
    ADIOI_Free(rbuf_copy_of_req_info);
    ADIOI_Free(count_others_req_per_proc);
    ADIOI_Free (scounts);
    ADIOI_Free (sdispls);
    ADIOI_Free (rcounts);
    ADIOI_Free (rdispls);

    *count_others_req_procs_ptr = count_others_req_procs;
#ifdef AGGREGATION_PROFILE
    MPE_Log_event (5027, 0, NULL);
#endif
    TRACE_ERR("Leaving ADIOI_GPFS_Calc_others_req\n");
}